Abstract

Zincblende Mn-rich Mn(Ga)As nanoclusters embedded in GaAs matrices are fabricated by in situ postgrowth annealing diluted magnetic semiconductor (Ga,Mn)As films with Mn concentration ranging from 2.6% to 8% at . Magnetization measurements show that memory effect and slow magnetic relaxation, the typical characteristics of the spin-glass-like phase, occur below the blocking temperature of in samples with high Mn concentration, while for samples with low Mn concentration, ferromagnetic order remains up to . The behavior of low-temperature spin dynamics can be explained by the hierarchical model.

Received 21 August 2007Accepted 28 October 2007Published online 14 November 2007

Acknowledgments:

The authors acknowledge J. F. Bi and Y. H. Zheng for their help on sample preparation, and Y. Zhang and H. Y. Zhang for SQUID measurements. The authors also thank H. Z. Zheng, Y. Ji, and X. G. Wu for valuable discussions. This work was supported partly by the National Natural Science Foundation of China under Grant Nos. 10334030, 0713130000, 60521001 and the special funds for the Major State Basic Research Contract No. 2007CB924903 of China, and the Knowledge Innovation Program Project of Chinese Academy of Sciences (KJCX2.YW.W09-1).